Asañña-satta: The unconscious beings, are a class of divine beings in the fine-material world. There are, Bhikkhus, divine beings known as the unconscious ones. As soon, however, as in those beings consciousness arises, those beings will vanish from that world. Now, Bhikkhus, it may happen that one of those beings after vanishing from that world, may reappear in this world. D. 24.
Maha Thera Nyanatiloka. Manual of Buddhist Terms and Doctrines, Buddhist Publication Society, first edition 1952.